Classifying and sorting apparatuses have been known in the art for many years and are useful for separating desirable and undesirable articles from a product stream using a variety of methods. The apparatus often found in the art include reflecting electromagnetic radiation in the form of light to determine the optical reflective characteristics of the articles in the product stream using color as a determinant. A notable example of such as sorter is the High Speed Mass Flow Sorting Apparatus for Optically Inspection and Sorting Bulk Food Products as shown in U.S. Pat. No. 5,887,073, which is incorporated by reference
U.S. Pat. No. 6,122,404 teaches a visible stokes polarimetric imager that uses a plurality of prisms and filters in conjunction with a imaging device. This device is disadvantaged because the imaging requires the optics to provide minimal distortion across the entire field of view. This requirement increases both the cost of the components as well as the initial setup and calibration requirements. Each pixel in a sensor array needs to be calibrated. Yet further, the imager requires a significant light input which increases the cost and energy requirements of the imager. The document is incorporated by reference.
The PCT publication WO 02/31473A1, also incorporated by reference, specifically teaches that the reflected light received from the products having the same polarization as the light beam generally does not contain useful information and is allowed to pass through the beam splitter and directed away from the detectors and not considered in the sorting decision process. It is also indicated that reflected radiation having the same polarization as the initial polarization does not contain useful information.
The subject invention for an apparatus and method for classifying and sorting articles overcomes the perceived shortcomings and detriments in the prior art apparatuses and methods and is the subject of the present patent.